The present invention relates generally to pressure sensors and, more particularly, to non-linear sensors having two variables with cross-dependency.
Piezo resistive devices, such as piezo resistive transducers (PRT), are commonly used in commercial systems such as stress or pressure sensor systems. Such PRTs are typically implemented in integrated circuits and semiconductor devices. In accordance with the piezo resistive effect, the resistivity of piezo resistive elements changes in response to strain from the applied mechanical or physical stress to the piezo resistive element. In integrated circuits and semiconductor devices, the piezo resistive elements of the PRT are arranged to be in contact with a diaphragm such that a force or pressure applied to the diaphragm and the PRT converts the mechanical stress on the piezo resistive elements into differential electrical outputs. This property is used to measure ambient pressure.
The resistivity of piezo resistive elements within PRTs exhibit temperature dependency. This property is used to measure ambient temperature. If the PRT is not balanced with respect to pressure, large errors result in the computation of temperature. To minimize this pressure dependency of temperature computation, conventional PRTs are designed to be balanced with respect to pressure. However, attempting to balance a PRT with respect to pressure is difficult to achieve and places a heavy constraint on the design and manufacture of PRTs.
Thus, there is a need for a method and system of calibration of piezo resistive devices to compensate for temperature and pressure cross-dependency that addresses or at least alleviates the above issues in conventional non-linear sensors having two variables with cross-dependency.